How do you tell whether a line is parallel, perpendicular, or oblique

I have finals in my classes next week, and I'm stuck on a problem that deals with geometry. It's asking to 'state the relationship between the lines Y= 3/4x+1 and Y= -4/3x-1' and then it asks to explain. I've looked in my math book and my notes but I couldn't find any help with this. Can anyone help please?

y = mx + b
m = slope

If lines are PARALLEL, the slopes (m) are EQUAL.
Example: y = 2x + 3 and y = 2x - 5 are parallel.

If lines are PERPENDICULAR, the slopes (m) are NEGATIVE RECIPROCALS
Example: y = (2/3)x + 1 and y = (-3/2)x are perpendicular

y = (3/4)x + 1
y = (-4/3)x - 1

The slopes are negative reciprocals of each other, making the lines perpendicular.

Eq of line is
y=mx+c
where m is slope and c is y intercept
now lets call slope of 1st eq as m1 and that of 2nd eq as m2
for the condition 1)parallel m1=m2 2)perpendicular m1*m2=-1 else 3) oblique
from your equations comparing with eq of line we can conclude that they are perpendicular . You tell me the reason.

Parallel have the same slope.
Perpendicular have opposite reciprocals e.g. -2=1/2.
Oblique, no relation in slopes.

e.g.
3/4=-4/3; perpendicular

These lines are perpendicular.
You know two lines are perpendicular when their slopes multiply to -1.
Basically, when the slopes are negative reciprocals of each other (ie. 1/3, -3; .25, -4)

Parallel lines have the same gradient
Lines are perpendicular if the sum of the gradients = -1
Those two lines are perpendicular as 3/4 x -4/3 = -1

Graph the problem . . . here's an online grapher . . . paste 'em in.

Do you mean (3/4)x or 3/(4x)? Proper placement of brackets are important when entering formulas.